Micro - Antimicrobials (Part 1) Flashcards
(121 cards)
1
Q
How do imipenem, aztreonam, and cephalosporins work?
A
They block cell wall synthesis by inhibiting cross-linking of peptidoglycans
2
Q
How do bacitracin and vancomycin work?
A
They block peptidoglycan synthesis
3
Q
What antibiotic works by disrupting bacterial/fungal cell membranes?
A
Polymyxins
4
Q
Sulfonamides and trimethoprim inhibit the synthesis of which molecules?
A
Nucleotides
5
Q
How do fluoroquinolones exhibit their antibacterial effects?
A
DNA topoisomerase inhibition
6
Q
Rifampin blocks the synthesis of what bacterial molecule?
A
mRNAs
7
Q
Chloramphenicol works by what mechanism?
A
It binds to the 50S ribosomal subunit and blocks the synthesis of protein
8
Q
Lincosamides work by what mechanism?
A
They bind to the 50S ribosomal subunit and block the synthesis of protein
9
Q
Streptogramins work by what mechanism?
A
They bind to the 50S ribosomal subunit and block the synthesis of protein
10
Q
Linezolid works by what mechanism?
A
It binds to the 50S ribosomal subunit and blocks the synthesis of protein
11
Q
Macrolides work by what mechanism?
A
They bind to the 50S ribosomal subunit and block the synthesis of protein
12
Q
Tetracyclines work by what mechanism?
A
They bind to the 30S ribosomal subunit and block the synthesis of protein
13
Q
Aminoglycosides work by what mechanism?
A
They bind to the 30S ribosomal subunit and block the synthesis of protein
14
Q
Name six antibiotics that are bacteriostatic.
A
Erythromycin, Clindamycin, Sulfamethoxazole, Trimethoprim, Tetracyclines, and Chloramphenicol (remember: were ECSTaTiC about bacteriostatics)
15
Q
Name six antibiotics that are bactericidal.
A
Vancomycin, Fluoroquinolones, Penicillin, Aminoglocysides, Cephalosporins, and Metronidazole (remember: Very Finely Proficient At Cell Murder)
16
Q
Penicillin _____ is administered intravenously; penicillin _____ is administered orally.
A
G; V
17
Q
Penicillin is the prototype for which class of antibiotics?
A
β-Lactams
18
Q
Penicillin blocks _____ to inhibit cross-linking and activates _____ enzymes as well.
A
Transpeptidase; autolytic
19
Q
Which types of bacteria are killed by penicillin?
A
Gram-positive cocci and rods, gram-negative cocci and spirochetes; bacteria with penicillinase are resistant
20
Q
What are the two major toxicities associated with penicillin treatment?
A
Hypersensitivity reactions and hemolytic anemia
21
Q
Methicillin, nafcillin, and dicloxacillin have the same mechanism of action as what class of antibiotics?
A
Penicillins
22
Q
What differentiates methicillin, nafcillin, and dicloxacillin from penicillin?
A
Methicillin, nafcillin, and dicloxacillin are resistant to penicillinase and are effective against bacteria like Staphylococcus aureus
23
Q
Methicillin, nafcillin, and dicloxacillin are resistant to penicillinase as a result of what difference in their structure?
A
A bulkier R group
24
Q
Methicillin, nafcillin, and dicloxacillin are narrow-spectrum antibiotics that are used clinically for the treatment of what conditions?
A
Staphylococcus aureus infections, except methicillin-resistant Staphylococcus aureus (remember: naf for staph)
25
Why are nafcillin and dicloxacillin ineffective against methicillin-resistant *Staphylococcus aureus*?
Because of altered penicillin-binding protein target sites
26
What are the two major toxicities associated with methicillin treatment?
Hypersensitivity reactions and interstitial nephritis
27
Which drug can be administered with ampicillin to make it more effective against penicillinase-producing organisms?
Clavulanic acid, an inhibitor of penicillinase
28
Which has greater oral availability: amoxicillin or ampicillin?
Am**O**xicillin has better **O**ral availability
29
Which drugs have a wider spectrum of effectiveness: ampicillin/amoxicillin or penicillin?
Ampicillin and amoxicillin have a broader spectrum of effectiveness (remember: **AMP**icillin is **Amp**ed up penicillin)
30
What are the three major toxicities caused by ampicillin and amoxicillin?
Hypersensitivity reactions, rash, and pseudomembranous colitis
31
In addition to some gram-positive bacteria, which gram-negative rods are susceptible to ampicillin and amoxicillin?
*H. influenzae*, *E. coli*, **L**isteria monocytogenes, **P**roteus mirabilis, Salmonella, *enterococci (remember: ampicillin/amoxicillin* **HELPS** kill enterocicci)
32
True or False? Ticarcillin, carbenicillin, and piperacillin are resistant to penicillinase.
False; but they can be used with clavulanic acid to give them resistance to penicillinase
33
Which bacteria are ticarcillin, carbenicillin, and piperacillin active against?
Gram-negative rods, including *Pseudomonas* (remember: **T**icarcillin, **C**arbenicillin, and **P**iperacillin **T**akes **C**are of **P**seudomonas)
34
What is a common toxicity of ticarcillin, carbenicillin, and piperacillin?
Hypersensitivity reactions
35
Cephalosporins belong to what class of drugs?
Beta-lactams
36
Are cephalosporins more or less susceptible to penicillinase than other β-lactams?
Less susceptible
37
Name two examples of first-generation cephalosporins.
Cefazolin and cephalexin
38
First-generation cephalosporins cover which organisms?
Gram-positive cocci, **P**roteus mirabilis, **E**scherichia **c**oli, and *Klebsiella pneumoniae*. (remember: **PEcK**)
39
Name three examples of second-generation cephalosporins.
Cefoxitin, cefaclor, and cefuroxime
40
Second-generation cephalosporins cover which organisms?
Gram-positive cocci, **H**aemophilus influenzae, **E**nterobacter aerogenes, **N**eisseria, **P**roteus mirabilis, **E**scherichia coli, **K**lebsiella pneumoniae, and **S**erratia marcescens (remember: **HEN PEcKS**)
41
Name three examples of third-generation cephalosporins.
Ceftriaxone, cefotaxime, and ceftazidime
42
Third-generation cephalosporins cover which organisms?
Serious gram-negative infections that are resistant to other β-lactams
43
Why are third-generation cephalosporins a good choice for treatment of meningitis?
Because they penetrate the blood-brain barrier
44
Which third-generation cephalosporin is used for *Pseudomonas* coverage?
Ceftazidime
45
Which cephalosporin is often used to treat gonorrhea?
Ceftriaxone
46
Name one example of a fourth-generation cephalosporin.
Cefepime
47
Fourth-generation cephalosporins are different from third-generation cephalosporins in that the fourth-generation drugs have increased activity against which organisms?
*Pseudomonas* and gram-positive organisms
48
True or False? Unlike penicillin, hypersensitivity reactions are not a major toxicity of cephalosporins.
False; hypersenstivity reactions are a potential toxocity of all cephalosporins
49
What is the likelihood that a penicillin-allergic patient is also allergic to cephalosporins?
There is cross-hypersensitivity in 5% to 10% of patients
50
What toxicity can occur in patients using cefamandole who drink alcohol?
A disulfiram-like reaction (applies to all cephalosporins with a methylthiotetrazole group)
51
Aztreonam is an example of what subclass of β-lactam drugs?
Monobactams
52
Is aztreonam susceptible to β-lactamases?
No; it is resistant to β-lactamases because it is a monobactam
53
Aztreonam inhibits cell wall synthesis by binding to what substance?
Penicillin binding protein 3
54
Aztreonam is synergistic with what class of drugs?
Aminoglycosides
55
Does aztreonam have any cross-allergenicity with penicillins?
No
56
Aztreonam is used to treat infection with what type of organisms?
Gram-negative rods (*Klebsiella, Pseudomonas*, and *Serratia*)
57
Which gram-positive and anaerobic bacteria does aztreonam have activity against?
None!
58
Aztreonam is used in which two patient groups who have infections caused by susceptible organisms?
Penicillin-allergic patients and those with renal insufficiency who cannot tolerate aminoglycosides
59
Aztreonams toxicity profile includes what side effects?
Aztreonam is usually nontoxic, although it may occasionally cause gastrointestinal upset
60
Imipenem is an example of what subclass of beta-lactams?
Carbapenems
61
Imipenem is a \_\_\_\_\_(broad-/narrow-) spectrum, β-lactamase-\_\_\_\_\_ (resistant/susceptible) carbapenem.
Broad; resistant
62
Imipenem is always administered with _____ to reduce inactivation in the _____ \_\_\_\_\_
Cilastatin; it is given to reduce inactivation in renal tubules (remember: the "kill is **Lastin** with ci**Lastin**)
63
Cilastatin is an inhibitor of what substance and thus given with imipenem?
Renal dehydropeptidase I
64
Imipenem is used to treat which kinds of infections?
Gram-positive cocci, gram-negative rods, and anaerobic infections
65
Imipenem/cilastatin and meropenem are the drugs of choice for infection by which bacteria?
*Enterobacter*
66
At what point during disease progression is imipenem or meropenem considered a treatment option? Why?
Only when other medications have failed or in life-threatening infections because of the significant adverse effects these two medications have
67
What are the toxicities associated with imipenem and meropenem?
Gastrointestinal distress, rashes, and seizures; adverse effects more commonly occur at high doses
68
Which has a higher risk of causing seizures imipenem or meropenem?
Imipenem
69
Why is meropenem not coadministered with cilastatin?
Because meropenem is stable to dehydropeptidase I
70
How does vancomycin work?
It binds the D-Ala D-Ala portions of cell wall precursors, thereby inhibiting cell wall mucopeptide formation
71
How do bacteria develop resistance to vancomycin?
Conversion of D-Ala D-Ala to D-Ala D-Lac
72
Vancomycin is used for multidrug-resistant gram-\_\_\_\_\_ (positive/negative) organisms.
Positive
73
Name two organisms for which vancomycin is commonly used.
Methicillin-resistant *Staphylococcus aureus* and *Clostridium difficile* (pseudomembranous colitis)
74
What types of toxicity are possible with vancomycin treatment?
**N**ephrotoxicity, **o**totoxicity, **t**hrombophlebitis, and diffuse flushing ("red man syndrome"), but in general it does **NOT** cause many problems
75
"Red man syndrome" with vancomycin administration can largely be prevented with pretreatment with _____ and with the use of a _____ (slow/fast) infusion rate.
Antihistamines; slow
76
Which protein-synthesis-inhibiting antibiotics are bactericidal?
Aminoglycosides
77
Which mnemonic addresses which protein synthesis inhibitors are 30S subunit inhibitors and which are 50S subunit inhibitors?
Buy **AT** 30, **CCELL** at 50 (**A**minoglycosides and **T**etracyclines at 30, **C**hloramphenicol, **C**lindamycin, **E**rythromycin, **L**incomycin and **L**inezolid at 50)
78
Name five aminoglycoside antibiotics.
Gentamicin, neomycin, amikacin, tobramycin, and streptomycin
79
Aminoglycosides block protein synthesis by the inhibition of _____ \_\_\_\_\_ formation, and they cause the misreading of \_\_\_\_\_.
Initiation complex; mRNA
80
Aminoglycosides require _____ for uptake and therefore are ineffective against \_\_\_\_\_.
Oxygen; anaerobes (remember: the aminoglycosides (**Mean**) gentamicin, neomycin, amikacin, tobramycin, and streptomycin (**GNATS**) can **NOT** (**N**ephrotoxicity, **Ototoxicity and Teratogen) kill anaerobes**
81
Are gentamicin, neomycin, amikacin, tobramycin, and streptomycin bactericidal or bacteriostatic?
Bactericidal
82
Aminoglycosides are used to treat severe infections by gram-\_\_\_\_\_ (negative/positive) _____ (cocci/rods).
Negative; rods
83
Aminoglycosides are synergistic with which class of antibiotics?
Beta-lactams
84
Neomycin is commonly used as part of preparation for what procedure?
Bowel surgery
85
What toxicities are associated with aminoglycosides?
**N**ephrotoxicity and **O**totoxicity; they are also **T**eratogenic (remember: mean **GNATS** can **NOT** kill anaerobes = Gentamicin, Neomycin, Amikacin, Tobramycin, Streptomycin)
86
Aminoglycosides’ nephrotoxic potential is increased when it is used with what class of antibiotics?
Cephalosporins
87
Aminoglycosides’ ototoxic potential is increased when it is used with what class of drug?
Loop diuretics
88
Name four antibiotics that belong to the class tetracyclines.
Tetracycline, doxycycline, demeclocycline, and minocycline
89
What is the mechanism of action of tetracyclines?
Tetracyclines bind to 30S and prevent the attachment of aminoacyl-tRNA
90
Do tetracyclines have good central nervous system penetration?
No; tetracyclines have limited central nervous system penetration
91
Which tetracycline-family drug is safe to use in patients with renal failure?
Doxycycline (fecally eliminated and therefore can be used by patients with renal failure)
92
Which foods and drugs should not be taken with tetracyclines? Why?
Milk, antacids, and iron-containing preparations, because divalent cations inhibit the absorption of doxycycline
93
Tetracyclines are used to treat infections with which two organisms that are transmitted by ticks?
*Borrelia burgdorferi* and *Rickettsia*
94
Tetracyclines are used to treat which skin infection?
Acne
95
Tetracyclines are avoided for use in children for what three reasons?
They discolor teeth, inhibit bone growth, and cause gastrointestinal distress
96
What dermatologic adverse effect results from use of tetracyclines?
Photosensitivity
97
Which tetracycline is used as a diuretic in patients with the syndrome of inappropriate antidiuretic hormone secretion?
Demeclocycline, because it is an antidiuretic hormone antagonist (remember: **D**emeclocycline = **D**iuretic)
98
Name ten bacteria that tetracyclines are active against.
**V***ibrio cholerae*, **A**cne, **C**hlamydia, **U**reaplasma, **U**realyticum, **M***ycoplasma pneumoniae*, **T**ularemia, **H**elicobacter pylori, **B**orrelia burgdorferi, **R***ickettsia* (remember: **VACUUM TH**e **B**ed **R**oom)
99
Can pregnant women take tetracyclines?
No; tetracyclines are contraindicated in pregnancy
100
Name three examples of macrolide antibiotics.
Erythromycin, azithromycin, and clarithromycin
101
Macrolides inhibit protein synthesis by binding to the _____ rRNA of the _____ (30S/50S) ribosomal subunit.
23S; 50S
102
The binding of macrolides to the 23S rRNA of the 50S ribosomal subunit blocks what cellular process and inhibits protein synthesis?
Translocation of the peptide chain
103
Macrolides are used to treat infection with which organisms?
Gram-positive cocci, *Mycoplasma, Legionella, Chlamydia*, and *Neisseria*
104
What three types of infections are treated with macrolides?
Upper respiratory infections, pneumonia, and sexually transmitted diseases
105
Streptococcal infections in patients who are allergic to penicillin are treated with which drugs?
Macrolides
106
What is the most common cause of noncompliance with macrolide treatment?
Gastrointestinal discomfort
107
Macrolides increase the serum concentration of which drugs?
Theophyllines and oral anticoagulants
108
Other than gastrointestinal upset, what are four other adverse effects of macrolides?
Acute cholestatic hepatitis, eosinophilia, skin rashes, and prolonged QT interval
109
Which macrolide antibiotic is most likely to cause a prolonged QT interval?
Erythromycin
110
Chloramphenicol inhibits the enzyme \_\_\_\_\_, which is part of the _____ (30S/50S) ribosomal subunit.
Peptidyltransferase; 50S
111
Chloramphenicol is used to treat what type of infection?
Meningitis; it is considered a last resort because of significant toxicities
112
Chloramphenicol is used to treat meningitis caused by what three organisms?
*Haemophilus influenzae, Neisseria meningitidis*, and *Streptococcus pneumoniae*
113
What are the three major toxicities of chloramphenicol?
Dose-dependent anemia, dose-independent aplastic anemia, and gray baby syndrome
114
Chloramphenicol causes gray baby syndrome in _____ \_\_\_\_\_ as a result of the lack of the liver enzyme \_\_\_\_\_-\_\_\_\_\_ \_\_\_\_\_.
Premature infants, UDP-glucuronyl transferase
115
At the 50S ribosomal subunit, clindamycin inhibits protein synthesis by blocking the formation of what?
Peptide bonds
116
Clindamycin is primarily used to treat what type of organisms?
Anaerobes such as *Bacteroides fragilis* and *Clostridium perfringens*
117
What are the three major toxicities associated with clindamycin?
Pseudomembranous colitis, fever, and diarrhea
118
Why does pseudomembranous colitis often occur following treatment with clindamycin?
Because it kills normal flora and allows overgrowth of *Clostridium difficile*
119
Name three sulfonamide antibiotics
Sulfamethoxazole, sulfisoxazole and sulfadiazine
120
What are sulfonamide antibiotics and how do they work?
They are para-aminobenzoic acid antimetabolites that stop the activity of dihydropteroate synthetase, preventing DNA synthesis
121
Sulfonamides are active against what organisms?
Gram-positive organisms, gram-negative organisms, *Nocardia*, and *Chlamydia*
